This document discusses IP voice technologies used in Cisco voice infrastructure. It describes the layers of a Cisco voice network including call processing, applications, and infrastructure layers. Call processing examples include Cisco Unified Communications Manager Express (CME), Cisco Unified Communications Manager Business Edition (CCMBE), and Cisco Unified Communications Manager (CCM). Application examples are Cisco Unity Express and Cisco Unity Connection. The infrastructure layer consists of routers and switches to enable an IP telephone network with redundancy and quality of service (QoS) to ensure high uptime.